Well drilling means



April 1959 H. A. GEHRKE WELL DRILLING MEANS 4 Sheets-Sheet 2 Filed Feb. 18, 1957 I r Wnf/A SM.

W M M mm 0 V W W. A. M A N A M. R E H Y B 9 4 R o m m 3 sm April 21, 1959 HA. GEHRKE WELL DRILLING MEANS 4 Sheets-Sheet 3 Eiled Feb. 18, 1957 INVENTOR HERMAM A. GEHRKE I FII: 2 8 6 ATTORNEY April 21, 1959 WELL Filed Fb. 1a, 1957 A. GEH RKE DRILLING MEANS 4 Sheets-Sheet 4 FIG. 13.

INVENTOR. HERMAN A. GE HRKE A 7' TORNE V yak/11% United States Patent WELL DRILLING MEANS Herman A. Gehrke, Augusta, Kans.

Application February 18, 1957, Serial No. 640,961

7 Claims. (Cl. 255-3) This invention relates to well drilling. In a more specific aspect this invention relates to the drilling of oil or natural gas wells. In a still more specific aspect this invention relates to the drilling of oil or natural gas wells wherein a drilling fluid is passed down into the bottom of the well hole during drilling. This drilling fluid picks up material removed from the bottom of the well hole during drilling and carries same to the surface. In yet a more specific aspect this invention relates to the drilling of oil or natural gas wells using percussion hammer drilling equipment in which operation a liquid drilling fluid is passed down into the bottom of the well hole being drilled wherein material removed by the percussion hammer bits is picked up and carried to the surface. And, still more specifically this invention relates to changing the usual pneumatic precussion drilling equipment to more efficiently and effectively handle the drilling fluid and material removed from bottom hole in drilling, and to so handle the well drilling process and means.

This is a continuation-in-part of my copending application Serial No. 605,334, filed August 21, 1956, and titled Oil Well Drilling Method and Means.

The common and usual pneumatic percussion drilling apparatus for drilling oil wells has a drill string of threadedly joined sections of drill pipe which is rotated at the surface by power means therefor, such power means being connected to the top section of pipe of the drill string to rotate the string, and thus reamer means which shapes the hole above the pneumatic drill hammers. And, means are provided to operate the pneumatic hammers which break up the material at the bottomof the well hole. The lower end of the lower section of drill pipe mounts the usual pneumatic hammer bit which removes material from bottom hole when the drilling operation is carried on. Drilling mud is pumped from the surface through the drill pipe to the well bottom during drilling where the hammers remove material from the bottom. This material is picked up by the drilling mud and is pased up to the surface in the annular space between the drill pipe and well hole. The material or breakings are separated from the mixture, the mud diluted and/or treated as otherwise desired, and passed back into the drill pipe for further use to pickup breakings. Relatively high pressure and large equipment are necessary to handle this usual mud circulation method, and enough pressure must be put on the mud stream at the surface to overcome the entire frictional loss due to flow down the drill pipe and back up the space between the drill pipe and well hole. Needless to say these losses are great due to the nature of the mud and the rough well hole walls. The typical drilling mud is relatively viscous due to necessity. Also, the well walls are in some instances such that loss of mud into formations is great, and large cavities, etc., in formations have resulted in loss of circulation completely and of practically the entire mud supply. In addition, the mud in contact with thewell wall has caused producing formations to be ice missed, or damaged to the extent that flow area from the formation is substantially decreased and the ultimate recovery from the field drastically curtailed. I have invented new means and methods for drilling wells using drilling fluids wherein the drilling fluid is always contained in the ground in the drill pipe or a conduit within the drill pipe except in the very bottom of the hole. The many disadvantages of the usual drilling method and means are overcome by the new devices, apparatus and methods of my invention.

The new well drilling means of my invention has percussion hammer drilling means which are mountable on the lower end portion of a drill string having drill pipe therein. A drilling fluid conduit mountable in the drill pipe is used. This conduit has means to carry drilling fluid to the bottom of the well hole during drilling, and means to carry drilling fluid and material removed from bottom hole to the surface. The conduit is operatively connectable to operate the hammer drill bit means during drilling operation. Means are provided to operate the conduit. In a preferred specific embodiment of the new well drilling means of my invention I employ in the drill string a compacting member, such as and preferably the compacting member disclosed in my copending application which has been referred to hereinbefore and which is operable upon rotation of the drill string. The compacting member serves to shape and condition the well wall. The new well drilling means of my invention is adapted upon operation to pass drilling fluid to bottom hole, to receive breakings from well bottom picked up by the drilling fluid, and to pass the resulting mixture back to the surface.

It is an object of this invention to provide new well drilling means.

It is another object of this invention to provide new means to drill oil or natural gas wells where drilling fluids are employed to bring material removed from the well hole to the surface.

It is a further object of this invention to provide new means to drill oil or natural gas wells by the percussion hammer method where drilling fluid is used to carry drill breakings or material from bottom hole to the surface.

Still a further object of this invention is to provide new means to cooperate in combination with the usual pipe string and powering assembly, with only slight change, to provide a new percussion hammer means wherein the .usual disadvantages associated with handling drilling fluid are eliminated.

Yet a further object of my invention is to provide new means for drilling an oil or natural gas well which are efficient, easy to operate, less expensive to manufacture and to use than the common type, and which are particularly reliable in operation.

Other objects and advantages of the new drilling means of my invention will become apparent to those skilled in the art upon reading this disclosure.

Drawings accompany and are a part of this disclosure. These drawings depict preferred specific embodiments of the new drilling means of my invention as applied to percussion hammer drilling, and it is to be understood that such is not to unduly limit the scope of my invention. In the drawings,

Fig. 1 is a schematic view in elevation of a preferred specific embodiment of the new drilling means of my invention in relation to auxiliary derrick means, and drilling fluid handling means.

Fig. 2 is an enlarged elevation view partly in cross section of the superstructure of the drill string which operates same, and which provides for introduction and withdrawal of the drilling fluids from the string.

Fig. 3 is an enlarged longitudinal elevation view partly in cross section of the compacting member in the drill string above the drill means thereof.

Fig. 4 is a view taken on line 4-4 of Fig. 3.

Fig. 5 is a view taken on line 5--5 of Fig. 3.

Fig. 6 is an enlarged longitudinal elevation view partly in cross section of the lower drill means of the drill string showing the percussion hammer working means.

Fig. 7 is a lower continuation of Fig. 6 showing the head means of the percussion hammers.

Fig. 8 is a view taken on line 8-8 of Fig. 6.

Fig. 9 is a view taken on line 9--9 of Fig. 6.

Fig. 10 is an enlarged elevation View showing means slidably mounting the hammers in the barrel or chamber of the drilling means on the bottom of the drill string (Figs. 6, 7 and 9).

Fig. 11 is a view taken on line 11-11 of Fig. 7.

Fig. 12 is a bottom plan view of a preferred hammer head design preferably used with the new drill means of my invention.

Fig. 13 is a bottom plan view of another preferred hammer head design.

Following is a discussion and description of the new drilling means of my invention made with reference to the drawings whereon the same reference numerals are used to indicate the same or similar parts or structure. The discussion and description is of preferred specific embodiments of the new drilling means of my invention, and it is to be understood that such is not to unduly limit the scope of my invention.

Referring now to Fig. 1, the new percussion hammer drilling means of my invention is used with the usual derrick structure 15, Kelly tool 17, and rotary table 19. These are employed in the usual manner. A common separating trough 21 is used for settling and separating the bottom hole breakings or material from the drilling fluid returned via preferably flexible line 23 to trough 21. These cuttings are suitably disposed of. The low viscosity drilling fluid, preferably substantially water, is returned to water supply tank 25 for reuse and reinjection into the well by pump 27 and via line 29. Line 29 is connected to a preferably flexible hose or line 31. This hose or line flexes in use as the drill string and operating equipment move up and down. A pipe 33 and small mud pump 35 are preferably provided to introduce mud into the well hole 37 between the drill string and well wall for sealing purposes, etc., if desired or required in operation.

Referring now to Figs. 6 through 13, the new drill string of my invention has drill means 40 on the lower end thereof, which upon operation breaks material from the bottom of the well hole 37 to deepen the hole. The drill means 40 has an outer cylindrical housing 42 which is threaded in its upper end portion to secure same in the drill string to a compacting member 45 or to a section of drill pipe 49, as desired. The housing 42 is preferably substantially the same in diameter as the drill pipe 49. The housing 42 contains and mounts the percussion hammer drill operating means. An inner closed barrel or chamber 44 is fixed in outer housing 42 by plate member 46 which is secured to housing 42 in any suitable manner, such as by welding, and by fixed plate member 48 which is held in position in housing 42 against the lower end of barrel 44 by anchoring ring 50 which is threadedly secured in housing 42. This means is particularly preferable to mount the barrel 44 and hammer operating means, because with such the hammer operating parts can be easily removed from the lower part of housing 42 for repair or replacement, etc. A plate 51 is mounted in the lower end of barrel 44 to seal the end of same, as does plate 46 seal the upper end of the barrel. Plate 46 has apertures 53 therethrough and plate 48 has apertures 55. These apertures along with the annular space between outer housing 42 and chamber or barrel 44 provide a passageway through the drill means for drilling fluid carrying bottom hole breakings.

A conduit pipe 52 is mounted in barrel 44. This conduit carries drilling fluid to well bottom during drilling, is connected to trip means to operate the percussion hammers during drilling, and is connected to conduit 54 which supplies drilling fluid from the surface and which has flight conveyor means to lift drilling fluid and breakings to the surface. Conduit 52 passes through a hole in plate 46 and is rotatably mounted therein in sealed relation by bushing 56. Below plate 46 is mounted bearings 58 and 60, which are spaced and anchored by separator 62 fixed to pipe conduit 52 in any suitable manner to keep same from moving longitudinal to the drill means 40. Bearing 58 is retained by plate 46 and anchor 62, and bearing 60 is retained by anchor 62 and plate 64. Plate 64 is held in barrel 44 by ring 66. This whole assembly is held together by bolts 68 passing through plates 46 and 64 and being threadedly secured in ring 66. Another plate 70 is mounted in barrel 44 below ring 66. Plate 52 passes therethrough, and is mounted in sealed relation to the plate 70 by bushing 72. The chambers between plates 46 and 64, and 64 and 70 are sealed to hold lubricant through which the rotating conduit 52 moves in operation. The lubricant is added through a hole in plate 46 sealed by plug 74, and in operation drips down through the small holes in plates 64 and 70 to the lower chambers to lubricate the moving parts, the lubricant level in the operating chamber being shown by line 76. Pipe conduit 52 extends through barrel 44 coaxial therewith and out the bottom of same through corresponding holes in plate 51 and 48.

Pipe 52 has a lifting shoe fixed thereto in any suitable manner, such as by a set screw 72. Shoe 80 rotates with pipe 52 in operation. This shoe has an inclined plane face portion 84, and in operation rollers 86 ride thereon, being picked up in the position shown for the roller on the right hand side of Fig. 6 and being dropped from in contact with shoe 80 and plane portion 84 in the position shown for the roller on the left hand side of Fig. 6. Shoe 80 is rotated in the direction shown by the arrow on Fig. 9. Rollers 86 are mounted on axle or pin members 88 which are secured in any suitable manner to slidably mounted members 90. These members 90 are mounted in slidable relation to barrel 44 on the inside thereof by bracket members 92 whose outer edges are spaced from the inner wall of barrel 44 to form channels in which the outer edges of members 90 ride. Brackets 92 can be mounted to engage two adjacent members 90 to hold same, and are preferably attached to barrel 44 by screw means 94 passing therethrough so that they can be removed easily. The upper end portions 96 of slide members 90 are turned inwardly and have holes therein which receive fixed rods 98, which are held in position by plate 70 and a plate 100. Plate 100 is held in position in barrel 44 by anchor ring 102 secured to the inner wall of barrel or chamber 44 in any suitable manner. Rods 98 have heads 104 held between plates 70 and 100, and plate 100 has a hole 101 therein to pass lubricant to the operating chamber. Spiral springs 106 are mounted on rods 98 between plate 100 and head portions 96 of slides 90. When shoe 80 alternately lifts slides 90 upon turning, these springs are compressed, and when the rollers 86 fall off inclined plane portion 84 of shoe 80, springs 106 act in compression to force slides 90 downwardly. Each of slides 90 has a hammer member secured thereto to move therewith. The shaft shanks 108 of the hammers are attached to slides 90 in any suitable manner, and they pnoject downwardly out of barrel 44 through plates 51 and 48 through which they slide. Bumper members 110 preferably of oil resistant hard rubber are mounted on shafts 103 to move therewith and are preferably anchored in place there on by members 112 fixed to shafts .108 in any suitablem-annera Upon operation when idling bumpers 110 cushion the blow against plate 51, and arrest the movement of the hammers when they are dropped by shoe 80. Packing 114 and 116 is used to seal shafts 108 and pipe 52 respectively, in relation to plates 51 and 48 to make the operating chamber of barrel 44 lubricant tight. An additional plate 118 to support shafts 108 is preferably mounted in the lower end portion of outer housing 42 and held therein by upper anchors 120 fixed to housing 42 and by lower anchor ring 122 secured in the housing in any suitable manner. This plate 118 has apertures 124 therethrough to pass drilling fluid and breakings from hole bottom for passage through the drill means 40. Shafts 108 have hammer heads 126 with teeth 128 on the lower end. These heads and teeth strike the bottom of the well hole in operation to break formation material therefrom. Conduit 52 extends down between the shafts 108 to the vicinity of heads 126 to deliver drilling fluid. In Fig. 12 is shown another preferred head 130 shape and arrangement of teeth, the heads having teeth 132, and still an other preferred hammer head and teeth arrangement is shown by heads 134 having teeth 136, Fig. 13. The embodiments of Figs. 12 and 13 have four heads 130 and 134, respectively, instead of the three heads 126 of the embodiment of Fig. 7. Each of the heads 130 and 134 have an operating shaft 108 attached thereto, making a total of four shafts 108 in each embodiment, and like the embodiment of Fig. 7, these shafts 108 move up and down in operation. The lower faces of hammer heads 130 and 134 have drilling teeth 132 and 136 thereon, respectively. The individual teeth 132 and 136 are like teeth 128 on heads 126 of the embodiment of Fig. 7. They have four faces and are pointed (as shown). In operation the teeth strike the bottom of the well hole to brake formation therefrom. With any head and teeth arrangement shown, substantially the entire bottom of the hole is struck by the hammers and teeth in operation as the drill string and outer housing 42 of drill means 40 is rotated. The anchor or retaining ring 122 is threaded to receive the common and usual reamer means used in oil well drilling, the shank of which 140 is shown secured to the end of housing 42 to turn therewith. The reamer shapes the hole above the hammers.

Referring now to Figs. 3, 4 and 5, the compacting member 45 of my invention is inserted in the drill string, preferably just above the drill means 40 and threadedly secured thereto to rotate therewith in operation. If desired, compacting member 45 can be mounted between sections of drill pipe 49. Compacting member 45 has an inner elongated and hollow housing 147 which is in conduit communication with holes 53 in plate 46, or the conduit of pipe 49. Around housing or pipe 147 is mounted an upper sleeve 149 and a lower sleeve 151. These sleeves mount roller compacting members 153 which have the ends of the shafts 155 therethrough mounted in bearings 157. These bearings are mounted in recesses therefor in sleeves 149 and 151. Member 147 is preferably longitudinally grooved on its outside to provide recesses wherein roller compacting means turn in operation as housing 147 is rotated with the drill string. Spiral springs 159 are mounted in and backed by housing 147, with their outer ends in contact with bearings 157 to urge same outwardly. In operation this provides for roller compacting means 153 to be pressed into contact with the wall hole 37, so that the surface of the rollers pack and shape the wall hole. And, compacting member 45 can be used to seal formations, etc., during operation with relatively heavy mud introduced through line 33 into the space between the drill string and well hole 37. As many compacting members 45 can be used as desired.

Next in the string preferably, and above the compacting member 45, is the usual drill pipe 49, and as many sections of same are used as is necessary to reach the surface for joining with the Kelly tool 17, which rotates the drill string to rotate drill means 40. The lower pipe 49 is threadedly secured to the upper end of: compacting member 45 to turn therewith as tool 17 turns the string, and the drill pipe is in conduit communication with compacting member 45 and the annular passageway through drill means 40. In the new drilling means of my invention the breakings or material removed from bottom hole by hammers 126 and teeth 128, are picked up by drilling fluid supplied through pipes 54 and 52. The breakings and fluid pass upwardly through drill means 40 as indicated by arrows 160 (Fig. 6). Pipe conduits 54 and 52 rotate in operation, preferably counter to the drill string, and the pipe 54 has a spiral flange 164 fixed thereto to provide a flight conveyor which picks up the breakings and drilling fluid and carries them to the surface, pipe 54 and flange 164 extending from the upper end of drill means 40 to the surface within the drill string. The conveyor is preferably made in sections approximately the same length as the drill pipe sections and suitably joinable, preferably threadedly joinable as the drill pipe sections, so additional flight conveyor sections can be added along with each drill pipe section. Lines 167 indicate the points of joining the sections of conveyor.

At the surface the drill string is rotated in the usual manner by the Kelly tool 17, and in the preferred specific embodiment shown, the Kelly tool is modified and adapted to also rotate pipe 54 counter to the drill striing. This is done by fixing a spur gear 169 to the top of the ielly tool 17 to turn therewith. This spur gear turns spur gear 171, which is fixed to turn shaft 173 journaled in the supporting framework having upper and lower supporting members 175 and 177,'respectively, such being connected and held together by threaded rods 179. Shaft 173 has a sprocket 181 fixed thereon to turn therewith. Chain 183 connects this sprocket to a sprocket 185 which is mounted on the upper end of the operating flight conveyor having a conduit 187 and a spiral flange 189. This drives pipe 187 counter the drill string and thus pipe 54 and 52 counter drill pipe 49, the compacting member 45, and drill means 40. I have found it preferable to gear such that the conveyor turns considerably faster than the drill pipe 49, a 4 to 1 ratio having been found preferable.

The lower platform supporting member 177 has a centrally located hole through which the Kelly tool 17 extends and in which it turns in operation. The usual mud header 191 can be employed, and is mounted in the framework above the gear 169 in any suitable manner. Header 191 has centrally located holes 193 and 195 therein through which the flight conveyor pipe 187 projects and in which it turns, and the breakings and drilling fluid are carried into header 191 and out outlet 23. This is reverse the flow of the usual mud header, but the usual header can be easily modified for this new use.

The whole of the framework is hung by U-bolt assembly 197 from block 199 operated by the tackle 201 and which is supported on the derrick 15. The block and frame work assembly as the well is drilled, and the block and tackle are used to raise the assembly for insertion of new sections of drill pipe 49 and conveyor pipe 54 into the drill string.

In operation the drilling fluid, preferably substantially water, is pumped by pump 27 into the top of pipe 187 through line 29 and hose 31 which is connected to rotating pipe 187 by any suitable water tight connector 205. The water flows down pipe 54 and 52 to the hammers as indicated by the arrows, and out around the heads 126 thereof, where it picks up the breakings from bottom hole. The water and breakings flow up through drill means 40. The flight conveyor 54-164 picks up the breakings and water and carries them to the surface and out line 23 to separating trough 21. The water separated is then recycled. Upon rotation of pipe 187 and thus pipe 52, shoe 80 rotataes, alternately picking 7 up and dropping plates 90 and hammers 108-126 to strike bottom hole and break up the material of the formation being drilled.

As will be evident to those skilled in the art, various modifications of this invention can be made, or followed,

in the light of this disclosure and discussion, without de- I parting from the spirit or scope of the disclosure or from the scope of the claims.

I claim:

1. Means for drilling an oil or natural gas well, comprising, in combination: bottom hole percussion drill means having an outer elongated cylindrical housing, an inner closed cylindrical chamber coaxially and fixedly mounted within said outer housing, said inner and outer housings defining an annular passageway through said drill means, a plurality of spaced percussion hammers slidably mounted within said inner chamber and extending out the bottom portion thereof to in drilling operation strike hole bottom to break up the formation of same, rotatable lifting shoe means operatively mounted within said inner chamber to contact during operation said hammers to alternately raise and release same to strike said hole bottom; a string of drill pipe threadedly secured in its lower end portion to the upper end portion of said drill means to turn same in operation, the conduit of said string of drill pipe being in direct flow communication with said annular passageway through said drill means; a compacting member threadedly secured in said string of drill pipe above said drill means to rotate therewith, said compacting member having an elongated hollow housing with the conduit resulting from said housing in direct flow communication with the conduit of said drill pipe of said drill string, said compacting member housing having a plurality of spaced roller packing members rotatably mounted around said compacting member housing on the outside thereof, and said packing members mounted to rotate upon rotation of said compacting member with said roller packing members in con tact with the walls in drilling; drilling fluid conduit pipe rotatably and coaxially mounted within and throughout the length of the conduit of said drill string and compacting member and through said chamber of said drill means to a point in the vicinity of the head of said hammers, said drilling fluid conduit pipe comprising, a plurality of sections of pipe threadedly secured together to turn together, each section of said pipe in said drill string and compacting member having spiral flange flight conveyor means on the outside thereof throughout the length thereof and said conduit pipe operatively connected to said shoe means of said drill means to operate some upon rotation of said pipe; means operatively connected to said string of drill pipe and said drilling fluid conduit pipe to rotate same in opposite directions; means to introduec drilling fluid into said pipe at the surface; and means to remove said drilling fluid and material removed from bottom hole passed to the surface; and said means for drilling an oil or natural gas Well adapted upon operation to remove material from the well bottom with such being picked up by drilling fluid passed to said hammers through said drilling fluid pipe, and with the resulting mixture of drilling fluid and material from well bottom passing through said annular passageway in said drill means and being conveyed to the surface by said flight conveyor within said drill pipe string and compacting member.

2. The means for drilling of claim 1 wherein the lower end portion of said outer cylindrical housing of said drill means is constructed to receive and mount for opera tion a common reamer drill bit.

3. Means for drilling an oil or natural gas well, comprising, in combination, a drill string having a lower drill means and a drill pipe with a-compacting member therein above said drill means, said drill means, drill pipe and comp acting member being in conduit connnunication, said drill means having percussion hammer means and a rotary lifting shoe means therefor operatively mounted in said drill means to raise and lower said hammer means to break material from hole bottom during operation, said drill means having a closed return passageway therethrough in communication with said drill pipe, said compacting member having a plurality of roller packing members mounted on the outside thereof in position to rollingly contact the hole wall to pack same during drilling operation, a drilling fluid conduit rotatably mounted within said drill pipe, compacting member and drill means and adapted in operation to deliver drilling fluid to hole bottom, said drilling fluid conduit in said drill pipe and compacting member having flight conveyor means therewith formed by a spiral flange around said conduit and said conduit operatively connected to said shoe means in said drill means to operate same and said hammers upon rotation of said conduit, means to rotate said drill string and said drilling fluid conduit, and said means for drilling an oil or natural gas well adapted upon operation to pass drilling fluid to bottom hole through said drilling fluid conduit, to receive drilling fluid and bottom hole material removed by said hammer means, and pass same through said return passageway in said drill means, drill pipe and compacting member up to the surface by said flight conveyor means.

4. Means for drilling a well, comprising, in combination, a drill string having a lower drill means and an upper drill pipe in conduit communication with said drill means, said drill means having percussion hammer means and means to work same operatively mounted to cause said hammer means to strike well bottom during drilling operation, said drill means having a closed return passageway therethrough in communication with said drill pipe, a drilling fluid conduit mounted for rotation within said drill pipe and to deliver drilling fluid to said well bottom, said conduit having mechanical conveyor means therewith and being operatively mounted to operate said means to work said hammer means upon rotation of said conduit, means to rotate said conduit during drilling operation, and said means for drilling a well adapted upon operation to pass drilling fluid to bottom hole through said conduit and pass drilling fluid and material removed from said bottom hole through said return passageway and said drill means and through said drill pipe.

5. The drilling means of claim 4 wherein said drill string has a compacting member therein above said drill means, and said compacting member has rotatable means operatively mounted to rollingly contact the Wall of the well during drilling.

6. The drilling means of claim 4 wherein said conveyor means is a flight conveyor with a spiral flange on the outside of said drilling fluid conduit.

7. Means for drilling a well, comprising, in combination, percussion hammer drilling means mountable on the lower end portion of a drill string having drill pipe means therein, said drilling means having a closed return passageway therethrough in communication with said drill pipe, a drilling fluid conduit mountable in said drill pipe, said conduit having means to carry drilling fluid to bottom hole during drilling, having mechanical conveyor means to carry drilling fluid and material removed from bottom hole to the surface, and operatively connectable to operate said hammer means during drilling operation, and means operatively connectable to operate the conduit.

References Cited in the file of this patent UNITED STATES PATENTS 758,781 Roelofson May 3, 1904 1,621,569 Wellensiek Mar. 22, 1927 1,748,341 Grant et a1 Feb. 25, 1930 2,241,712 McNamara May 13, 1941 2,670,046 Zinzbach Feb. 23, 1954 2,742,264 Snyder Apr. 17, 1956 

